IBM REDBOOKS JUNE RELEASED

PowerVM Virtualization Active Memory Sharing

Revised: June 19, 2009

http://www.redbooks.ibm.com/redpapers/abstracts/redp4470.html?Open

DS8000 Disk Encryption Implementation & Usage Guidelines

Revised: June 15, 2009

http://www.redbooks.ibm.com/redpapers/abstracts/redp4500.html?Open

N-Series Operation & Protection Manager to Manage Your Unified Storage Environment

Published: June 19, 2009

http://w3.itso.ibm.com/redpieces/abstracts/sg247734.html?Open

Brocade 10Gb CNA for IBM System-x

Published: June 16, 2009

http://www.redbooks.ibm.com/abstracts/tips0718.html?Open

QLogic 10Gb CNA for IBM System-x

Published: June 16, 2009

http://www.redbooks.ibm.com/abstracts/tips0720.html?Open

Frequent Print Error Messages

My friend called me this evening asking me to help with her problem regarding adding print queue.. Error 0781-017 . As i was driving, i can only help her once i stop driving and reached office. In the meantime, she told me she use google and manage to find the answer. She was nice enough to give the link to me.

http://www-01.ibm.com/support/docview.wss?uid=isg3T1000284

Problem
Frequent Print Error Messages

Solution

This document describes some of the more common printing error messages, and outlines some solutions to resolve these problems. This document applies to AIX Version 4.3 and later.

Hey, i got some interesting link that you people wanna try.

www.postful.com - send an email and turn to physical mail. Design post card on line and send it in physical postcard. Cool. www.jott.com - call a simple phone number, speak your notes, messages, or updates and hang up. Jott Voicemail works the same way, but your friends, family, and colleagues are the ones leaving the messages when they call your number. Then, Jott takes the spoken messages, turns them into text, and sends them to the right destination via email, text message, or web update. www.telegram.com - hey, i won't give it all to you, eh? Try it and found out what it's all about.

IBM REDBOOKS MAY RELEASED

somebody pass me this info. Once in a while ibm will publish redbooks also known as technical guide or manuals or cookbook. Use to be the books are in red cover and hence redbooks. Will update latest redbooks on pSeries/AIX if my friend decided to do pass me the info.

p6-570 Technical Overview and Introduction.
http://www.redbooks.ibm.com/redpieces/abstracts/redp4405.html?Open

Intro: DS5000 Series. ISBN: 073843244X 666 pages
http://www.redbooks.ibm.com/abstracts/sg247676.html?Open

AIX Enterprise Edition Sys Admin Guide.ISBN: 0738432903 316 pages
http://www.redbooks.ibm.com/abstracts/sg247738.html?Open

p6-550 Technical Overview
http://www.redbooks.ibm.com/redpapers/abstracts/redp4404.html?Open

Utility Capacity on Demand: What Utility CoD Is and How to Use It

http://www.redbooks.ibm.com/redpapers/abstracts/redp4416.html?Open

PowerVM Virtualization Active Memory Sharing
http://www.redbooks.ibm.com/redpapers/abstracts/redp4470.html?Open

Understanding How AIX Manages Memory / Page Space

Somebody ask me about paging space. So I went to google to find out more and found an article which i think is still relevant eventhough AIX is at 6.1. The article dated back in 2001.

Data is essentially held in pages of 4096b, and a page in RAM is accessible by the CPU, if the page is on disk the CPU can't access it directly. A page fault occurs when a wanted page address does not translate to a real memory address (i.e. the data you wanted is not there). At this point the Virtual Memory Manager (VMM)knows it needs to get data from disk and place it in RAM - it therefore checks to see that there is space in RAM in which to out this data.

If there's enough room, VMM checks to see if the wanted page has been used previously by this process:

- if not, an "initial page fault", VMM allocates _two_ pages for the data; one in RAM and the other on a backing page on disk where it can go if it has to be temporarily removed from RAM. This is known as "late page space allocation".

- if it has, a "repage fault" I/O is scheduled to bring the data back from disk and into RAM - the act of resolving this repage fault is called a "page-in" (the process that is waiting for this to happen is in a "page wait state").

So what happens if there's not enough room in RAM to put the page? Well the page stealer is there to ensure that there is a supply of free RAM pages available for an initial page fault. If the number of free RAM pages drops below a specified value then the page stealer will try and get some pages back. It keeps on stealing pages until it reaches an upper limit.

So how does it decide which pages to steal? The page stealer will select the least recently used, or LRU, pages. If the page has been modified in RAM it's classed as a dirty page and is put to a backing store (either page space or a filesystem); if it's clean (the copy in RAM matches the copy in page space) then the RAM page is purged.

Note that the page space is used for non-persistent or working pages, and the filesystem is used for persistent or file pages.

There is, of course, a basic assumption here that all stale pages are treated equally, i.e. whether it's a file- or nonfile- page makes no difference to the page stealer.

However this is not the case. Increased paging activity makes VMM act upon the different types of (stale) pages in a different manner. When the number of [stale] file pages exceed a number - set by the maxperm threshold - the page stealer will steal only file pages.

If the number of stale file pages is below maxperm (but above the set minperm threshold) then two other considerations come into play.

The VMM checks the repage rates of both file and nonfile pages, and will steal file pages if the file page repage rate is higher than the repage rate for nonfiles.

If this not the case then both types of pages are treated as equal victims.

PERFORMANCE HITS / ACTUAL DISK I/O...

To understand the performance hit of the paging figures that you come across, you need to realise that page faults do NOT (necessarily) result in disk activity. Remember from above that only the repage fault - the act of bringing back previously used data into memory - causes disk I/O to be scheduled.

Page out I/O only occurs when a page is stolen by the page stealer AND is marked as 'dirty'. This only happens when there is a shortage of free RAM pages. Hence the page-out figure can be an indicator of how memory constrained the system is. The vmstat command is only of limited use as it just reports activity concerned with page space (and not paging to/from filesystem space).

If the system consistently appears to hover around the minperm value (the "fre" column in vmstat) then it does not follow that the system is memory constrained - consider the scenario where an initial page fault is resolved by purging a clean, but stale, page. In this there is paging activity but no corresponding I/O.

System performance may be improved by reducing the amount of RAM that file pages occupy - this ensures that working pages are not continually being pushed out to make way for file pages.

This can be achieved through the use of the vmtune command (/usr/samples/kernel) and DECREASING values for minperm and maxperm.

PAGING SPACE

So how much page space do I need? For systems that have up to 256MB of real memory, use the well known formula...

page_space = 2 x real_memory

...for those systems with more than 256MB of real memory use...

page_space = 512MB + (real_memory - 256MB) * 1.25

The following should also be adhered to where possible:

1. configure just one paging space per disk
2. use between 2 and 6 paging spaces in a medium size system
3. configure the paging spaces on each disk to be the same size

That's about it really - all you never needed to know about paging space and VMM.

Dave V.

Thks dave for a good article in AIX paging. In my experience, which is not that much, for system that used Oracle, usually i will ensure that the paging space is 3 times of real memory. For Informix usually 3 times of real memory. As for DB2 just use default setting when you install AIX. For those who are really technical, try this for a change on Overview of AIX page replacement.
http://www.ibm.com/developerworks/aix/library/au-vmm/index.html

Where to find technical docs

My first posting. Let see, when i ordered my pSeries machines, i cannot find those thick manuals that i used to get when i ordered pSeries machines (back then known as RISC6000). So i search the web and found this website.

http://publib16.boulder.ibm.com/pseries/en_US/infocenter/base/aix51.htm

Contains information on topics shown below and specifically on AIX 5.1
System Management Guides
Installation Guides
System User's Guide
Programming Guides
Product and Apps docs
Reference Doc
Technical References

If any of people out there wants to ask Qs pls post your comment. I will try to find out more. Good for you since somebody can answer your Questions and good for me cause i can brush up my skill in AIX.